Welcome to my blog. I will attempt to make it much more than just a pitiful list of the relentlessly mundane minutiae of my daily existence but if you feel that I have failed try to imagine all the stuff that I haven't posted.

Tuesday, 26 April 2011

Lateral thinking

The best thing about the slightly vague open idea of this project is the chance to take an idea in a previously unconsidered direction.

My visit to the quarry in the north of Cambridgeshire with the Archeologists was particularly interesting. I managed to get samples of various clays that are rarely exposed, that have been laid down in quite specific time frames - from the Jurassic until the last ice age that extended across East Anglia. The site also contains samples of pottery from Neolithic, Bronze Age, Iron Age and Roman times, which this image illustrates.
Not only am I investigating these clays for my own use but am helping the Archeologists ascertain which clay deposits were used by potters in these different eras. My next task is to fire samples of these pot shards to different temperatures, along with test bars of the clays to compare colour, texture and porosity as the clays progressively fuse.
It is surprising just how lacking in strength (low-fired) most of these samples are. It is only the Roman that shows signs of maturity and along with the late Iron Age sample, any strength at all.

Thursday, 14 April 2011

The Kingdom of Rain

A quick post from the breathtakingly beautiful Lake District. Had a couple of glorious days and now am getting a long demonstration of why there is so much moss around on everything.

Last time I was up here I had a thick mane (?) of dark hair and my rucksack was full of beer and provisions rather than rock samples......

Friday, 8 April 2011

Clays of Cambridgeshire

So.....I've sorted through the various deposits I sampled at the archeological dig site and made shrinkage bars and test rings. All of the deposits were quite fine - very little grit at all, except for the glacial silt layer at the top. The Oxford clay (Jurassic period) was the only sample that needed work (crushing and slaking) before is became usable, but is a nice plastic, though not too sticky, clay. The river deposits were mostly usable as found, though two are very high in organic material and so unusable. These clays have varying amounts of fine silt in them and are generally highly sticky with a very high dry shrinkage.
I dried the samples, treated them with hydrochloric acid, washed them and dried them agian - to ascertain the calcium carbonate content. Oxford clay is high at around 20%. All the river deposits have some calcium content, though that for the 'buttery clay' and the 'rodden silt' seems lowish at 3 - 5%.

This image shows the tests fired to 1000C. As you can see, a few of the samples have developed such bad fire cracks that they have fallen apart - these are not the ones with the high organic content - but a few have held together and will form the basis for my next test mixtures.
I will fire these clays to 800C, 1100C and 1200C to see how they cope, colour and porosity. I will also be using these tests to help the archeologists ascertain which clays were used by the bronze age and iron age settlers here.
All this plus more biaxials and lineblends for a cone 11 glaze firing - I can hardly control my excitement!